Major Research Areas:

This laboratory is interested in two major research areas: large-scale cloning and analyses of genes involved in early cotton fiber development, and regulatory mechanisms of transcription factors in Arabidopsis shoot and root meristem development. Using cDNA prepared from 10dpa (days post anthesis) wild-type cotton fiber as tester and cDNA from a fuzzless-lintless (fl) mutant as driver, we applied the RDA method to recover 280 independent cDNA fragments related directly to early cotton fiber development. cDNA microarrays showed that 172 genes were significantly up-regulated in elongating cotton fibers as confirmed by in situ hybridization in representative cases. Twenty-nine cDNAs, including a putative vacuolar (H+)-ATPase catalytic subunit, a kinesin-like calmodulin binding protein, several arabinogalactan proteins and key enzymes involved in long chain fatty acid biosynthesis, accumulated to greater than 50-fold in 10 dpa fiber cells when compared to that in 0 dpa ovules. Various upstream pathways, such as auxin signal transduction, the MAP kinase pathway, and profilin- and expansin-induced cell wall loosening, were also activated during the fast fiber elongation period. Large-scale transcriptome profiling revealed that the plant hormone ethylene is involved in regulation of cotton fiber elongation growth and very long chain fatty acids participated in cell elongation growth by controlling the biosynthesis of ethylene in developing cotton fiber cells.

The lab is also involved in cloning and expressional analyses of 8 large gene families (AP2-EREBP、bHLH、C3H-TYPE2(Zn)、E2F-DP、HMG-BOX、NIN-like、PCG、TCP) encoding Arabidopsis transcription factors. WUS1 has been extensively studied and identified as a master regulator for specification of shoot stem cell fate in Arabidopsis. A network of regulators including not only canonical transcriptional factors like Apetala 2 (AP2) , Class III HD-ZIP family proteins including CORONA, PHABULOSA, PHAVOLUTA and REVOLUTA, together with the chromatin remodeling factor SPLAYED (SYD), function to precisely tune the transcription of WUS1. We observed severe SAM defects in the Arabidopsis knock-out mutant, bard1-3 (homologue of a breast cancer suppressor in human). Disordered cell division and dysfunction in differentiation was found in bard1-3 mutant. WUS1 transcripts accumulated to more than 238-fold in bard1-3 compared to wild-type and were located mainly in the outermost cell layers instead of the usual organizing center (OC). Increased BARD1 expression in CaMV35S::BARD1 transgenic plants reduced WUS transcript levels to about 25% of wild-type and resulted in a wus-1-like phenotype. Consistent with the restricted expression pattern of WUS1 in OC, predicated nucleosome positioning indicated the occupation of nucleosomes in WUS1 promoter region. Extensive protein motif analysis suggested a potential plant homeo domain (PHD) in the middle region of BARD1, which was reported to recognize H3K4Me3 on histone H3 tail.

Laboratory Introduction